Device for determining the radiation absorption distribution in a three-dimensional examination zone

Abstract

A device for determining the radiation absorption distribution in a three-dimensional examination zone which is irradiated from different positions which are situated in one plane and in which radiation sources are present. The device comprises two detector arrays consisting of separate, adjacently arranged detectors, which are situated at a distance from and parallel to each other in a first plane and in a second plane. The device further comprises radiation sources which are situated between the two extreme planes and which are arranged to be rotate around an axis of rotation which extends transversely of said planes. The radiation sources are line-shaped and are arranged parallel to the axis of rotation and diametrically with respect to the axis of rotation opposite a detector array.

What is claimed is: 
     
       1. In a device for determining a radiation absorption distribution in a three-dimensional examination zone comprising: radiation sources which are situated in one plane and which irradiate the examination zone from different directions; detectors which detect the radiation which has passed through the examination zone and supply sets of output signals which are characteristic of the absorption of the radiation; and an arithmetic device which reconstructs the radiation absorption distribution on the basis of the output signals, the improvement wherein the radiation sources are arranged in a radiation source plane which is equidistant from an axis of rotation, the axis of rotation extending transversely to a first plane and a second plane, situated at a distance from and parallel to each other, the radiation sources being adjacently situated parallel to and rotatable around the axis of rotation and the detectors comprise at least two detector arrays which extend transversely to the axis of rotation and which consist of separate, adjacently situated detectors, said detector arrays being arranged in the said two planes, diametrically opposite the radiation sources with respect to the axis of rotation. 
     
     
       2. A device as claimed in claim 1, wherein the detector array is a ring of detectors. 
     
     
       3. A device as claimed in claim 2, further comprising a holder; a support disposed on the holder which support is rotatable around the axis of rotation; two radiation source arrays situated on the support, which arrays are remote from each other in a direction of rotation and which are arranged on a straight line, said source arrays extending from the first plane to the second plane; and two identical detector array rings each of which rings is irradiated by one radiation source array, the axis of rotation extending through the centers of the rings. 
     
     
       4. A device as claimed in claims 1, 2 or 3, further comprising collimator means associated with each radiation source which direct the radiation onto a part of the associated ring of detectors. 
     
     
       5. A device as claimed in claims 1, 2 or 3 wherein the radiation sources comprise X-ray tubes, the X-ray emission point in which is movable along a rod-shaped anode by deflection of an electron beam. 
     
     
       6. A device as claimed in claim 4 wherein the radiation sources comprise X-ray tubes, the X-ray emission point in which is movable along a rod-shaped anode by deflection of an electron beam.